In a process of connecting the ends of coils to external power supply terminals in a small brushless motor, in general, wire treatment is performed using terminals and a treated part is soldered to have electric conduction.
For instance, a representative example is disclosed in JP-A-6-46543. In this example, a core has a plurality of salient poles extending radially from a ring part and coils are wound around the salient poles. Further, slots between the salient poles have terminals, and the ends of coils are connected to the terminals by winding. The terminals have coil end winding portions which are formed so as to be bent in the axial direction of the core and can be soldered onto external power supply terminals, each being arranged at a position on one side of the coil along the axial direction of the core. Such terminals are often used for small brushless motors.
Another publicly known technique is disclosed in JP-A-4-193053. Conventionally, a resin-molded insulator has been frequently placed on an end face of a core to secure insulation between the core and a coil. In such a publicly known technique, a terminal of a thin metallic plate is embedded into a part of the insulator, the part corresponding to a salient pole. Then, the coil is wound and held so as to bind the salient pole and the terminal. A coil end winding portion on the end of the terminal is formed so as to be bent in the axial direction and is soldered onto a printed wiring board which is adjacent to one side of the coil. With such a configuration, since the terminals are held by the salient poles, even thin and small terminals can be correctly positioned and soldered on external power supply terminals.
In the case of electronic equipment, when an electronic component is mounted on a printed board, soldering is performed according to a method of dipping into a soldering bath, a method of melting cream solder by reflow heating, and so on. However, as global environmental pollution has been a focus of attention in recent years, lead contained in a soldering material has become controversial. For this reason, in a component mounting process, a soldering material containing lead has been converted to a lead-free soldering material. The same demand is made on motors and conversion is demanded to a lead-free soldering material or a method of using no soldering material.
In response to such a demand, a lead-free soldering material may be selected. However, there is another factor that forces conversion to a joining method using no soldering material. For example, in a motor configured such that reflow mounting can be made on a substrate of a mobile phone, when a soldered part exists in the motor, heat of reflow heating is conducted to the soldered part and causes melting again because the motor is quite small. Such a problem has not been found in conventional motors which have not been devised based on reflow mounting. However, this problem is expected to be a significant problem to be solved for microminiature motors which will increase in number. In order to respond to this problem, conversion should be made to a joining method using no soldering material.
As a method of making electrical connection using no soldering material on a wire-treated part of winding, for example, a fusing method disclosed in JP-A-63-228937 has been known. In this technique, a terminal is adjacent to a coil wound around a core and has a hook. The winding terminal of the coil is connected to the terminal via the hook, and then, joining is performed by heating the hook by energization and applying pressure thereon.
However, the fusing method requires a large vacant space around the terminal. This is because it is necessary to pass a tool for heating by energization while sandwiching the hook of the terminal between both sides and applying pressure thereon. Therefore, this method is not applicable to a small and high-density motor which does not have a sufficient space around a terminal.